Method or art of making molds



C. PACK AND L. F. NOCK.

METHOD 0R ART OF MAKING MOLDS.

APPLICMlON HLED mu. 5, 1911.

Patented July 8, 1919. e 49' III/IIIII/ A 8 @414 e @{A e l e2 w 55155.- V O INVENTORS e e BY Z W UNITED STATES PATENT OFFICE.

CHARLES PACK AND LEO FRANK NOOK, F BROOKLYN, NEW YORK, ABBIGNOBIS 'IO DOEHLER DIE CASTING COMPANY, OF BROOKLYN, NEW YORK, A CORPORATION OF NEW YORK.

METHOD OR Alf! OI HAKING HOLDS.

Specification of Letters Patent.

Patented July 8, 1919.

Application flledlanuary fi, 1917. Serial m. 140,705.

To all whom it may concern:

Be it known that we, CHARLES PACK and Lao FRANK Noon, both citizens of the United States, residing at the borough of Brooklyn, in the city of New York, county of Kings, and State of New York, have jointly invented certain new and useful Improvements in Methods or Art of Making Molds, of which the following is a specification, reference being had therein to the accompanying drawings, which form a part thereof.

Our invention relates to the method or art of making molds and more particularly to making molds of plastic material for the production of machine parts.

Finished castings of low fusing white metal alloys and higher fusing alloys rich in aluminum have heretofore been made in large quantities, by what is known as the pressure die casting process. In this process steel dies are used, the casting being drawn therefrom throu h the separation of different arts of t e mold or die. The mechanica features of the die place certain limitations upon the character, design or contour of arts which can be produced; and the rapid eterioration of the mold has precluded the advantageous commercial use of brass and bronze in the production of finished castings. To permit the production of brass or bronze machine parts upon a commercial basis, recent developments have been made in the castin art, which contemplate the use of mol s made of plastic material, which molds after the metal has been poured thereinto, are broken away from the completed casting so that those limitations due to the necessity for providing for the drawing of the casting from the mold, are eliminated.

It is essential, however, to em loy difierent methods for producing mol s of different types, some castings being susceptible of production by means of sectional or split molds while others must be made by means of integral molds. The same methods, however, are not adapted for the production of different split molds. It is the practice in making split molds to use machine finished metal atterns, and the method employed in pro ucing a mold therefrom must be such as to permit the removal of this pattern, or

a plurality of such patterns, without fracturing or chipping the plastic material of the mold.

With this condition in mind, our present invention relates to a method or art of makin molds from a attern or patterns requlring that a portion of the mold cavity be formed in one section of the mold, and a portion thereof in another section of the mold in a manner to secure a perfect match of the mold cavities in the two sections. A mold made in accordance with our invention adapts itself to the production of a plurality of castings at one pouring. The chilling of the metal is so controlled as to insure the filling of the mold and the gate is so formed as to facilitate the flow of the metal to the Various mold cavities so as not to interfere with the drawing of the several patterns.

A mold made 1n accordance Wlth our invention possesses a sufiicient degree of porosity to afford ample venting facility, and a lar e number of such molds may be rapidly an? economically produced and all will possess such exactitude in the dimension and arrangement of the various mold cavities as to insure uniformity in the results from eastingl operations in diflerent molds.

he invention consists primarily in a method or art of making molds consisting in lacing a pattern within a frame upon a sla flowing a plastic composition into the frame, agitating said lastic composition about the pattern, allowing the composition to set, reversing the frame with the plastic mass therein, positioning a gate pattern thereon with a lead thereof in engagement with the pattern embedded in the plastic composition, placing a second frame upon said first frame, fiowin plastic composition into said last named rame, allowin said composition to set, separating the rames and drawin the patterns from the plastic mass in sac of said frames; and in such other novel steps and practices as are hereinafter set forth and described and more particularly pointed out in the claims hereto appended.

Referring to the drawings Figure 1 is a vertical section through a portion of a mold ready for the separation ofthe frames and the drawing of the patterns;

Fig. 2 is a plan view of the lower section of the mold;

Fig. 3 is a bottom plan view of the upper section of the mold;

Fig. 4 is a perspective view of one of the patterns usedand Fig. 5 is a plan view of the gate attern.

Like letters refer to like parts t roughout the several views.

In the commercial practice of our invention, it is customa to produce a mold having a plurality 0 cavlties therein and in the accompanying drawing, we have illustrated such a mold. In the practice of our method or art, we place a pluralit of patterns such as a within a frame a a apted to confine a sufiicient mass of the plastlc composition and upon a fiat slab b, the face of which conforms with the lower face of the pattern so as to prevent the fluid or viscous composition entering beneath the pattern. Each of the patterns a is provided with a stem at projecting to substantially the height of the frame a so as to facilitate the drawing of the patterns. Thereafter a plastic comosition preferably consisting of plaster of aris, kieselguhr or cellite and a fluid is flowed into the frame 0 to approximately the level of the top thereof. While the said plastic composition is still fluid it is agitated about each of the patterns to free any air which may be imprisoned in angles or cavities therein and after being so agitated the plastic mass at is allowed to set.

When the plastic mass has set in the manner above referred to, the mold is inverted exposing one face of the patterns and a smooth surface of the lastic material which has set against the sla When the frame 0 has been thus inverted, a pattern having a main ingate e, a wide run e and branch gates e is placed upon the 'plastic mass all with the said branch gates e resting upon the patterns a respectively.

A second mold frame f is then superimposed upon the frame 0 and plastic composition of the character above referred to is flowed into said frame 1 upon the plastic mass d and about the exposed to s of the patterns a and the gate pattern. f desired this plastic composition while still in a fluid state may be agitated about the top of the patterns a to free any imprisoned air, and thereafter the plastic is allowed to set.

When the plastic in the mold f has solidilied to the desired extent, the mold sections are separated, there being no tendency of the plastic mass 9 within the frame f to bond to the plastic mass d in the frame 0. the frame has been thus separated the. pattern e is drawn from the mass f and the several patterns a are drawn from the mass (1 by inverting the same and applyin rectilineal stresses to the projections a. here- After after the mold is heat dried in the usual manner.

The projections a form chill openings exposed through what becomes the bottom of the mold in pouring so that by resting the mold upon a surface of metal or metal coated with a thin layer of refractory material, the chilling of the casting is effected at a point remote from the ingate to each mold cavity, and any tendency in the chilling of the mold about the ingate in a manner to interfere with the proper filling of the mold cavity is avoided.

The arrangement of the main ingate 6, run 6' and branch gates e is such as to prevent oxids or other dross entering the mold cavity, the main ingate being large in section relative to the run 6' and branch gates 6 so that there will be a slight retardation of the flow, or skimming action, in the main ingate, causing the pure metal to drop through the main ingate while thelighter dross is held up. Also by forming the gate in the manner described the sprues upon the castings will be so positioned as to be readily removed without interfering with the parts of the casting having small dimensions or requiring accuracy of dimension.

The surplus metal formed by the section of the mo d cavity produced by the extensions a may readily be removed, the drilling of the hub, when a gear is made, (and the method of making the mold is especially adapted for the production of gears) removing this surplus metal.

In casting, the ordinary pouring methods may be emplo ed, the castings be ng drawn from the mol by the breaking down of the plastic mass about same.

A mold made in accordance with our invention may be used for casting metals having either low or high fusing points and the same patterns may be repeatedly used in making a number of molds. By using the projections a which are in the nature of ejector pins, the stresses in drawing the patterns may be so overned, as to insure the proper draft of t e pattern in leavin the mold and minimize any tendency o the breaking down of any of the small dimension projections in the mold cavity. By tapering the pro ections or pins slightly. the necessity for providing the pattern itself with any substantial draft is avoided, as air may be admitted through the openings formed by said projections or pinsinto the mold cavity as the patterns leave the mold, thus overcoming the eflect of suction as the patterns are withdrawn.

It is not our intention to limit the invention to the particular contour of the mold or patterns shown in the accompanying drawings, this showing being merely for the purpose of illustrating the practice of our method or art. Only patterns having one face thereof so formed as to permit the separation of the molds, may be used in the practice of our method or art.

In molds produced in accordance with our invention, no fins are formed u n the castings because of the very fine Joint secured between the two arts of the mold as a result of the use of the fluid or viscous composition in the frame f.

To secure an absolute register of the two sections of the mold, one or more cavities h are formed in the mass d by means of patterns h, when forming this section of the mold, so that when the section 9 is formed corresponding tongues i will be formed thereon.

Having described the invention what we claim as new and desire to have protected by Letters Patent is 1. The method or art of making molds consisting in lacing a pattern wlthin a frame upon a s ab, flowing plastic composition into the frame, agitating said plastic composition about the pattern, allowing the composition to set reversing the frame with the plastic mass therein, ositioning a gate pattern thereon with the ead thereof in engagement with the pattern embedded in the plastic composition, placing a second frame upon said first frame, flowing plastic composltion into the said last named frame, allowing said com osition to set, separating the frames and d i'awing the patterns from the plastic mass in each of said frames.

2. The method or art of making molds consisting in placing a plurality of independent patterns within a frame upon a slab, flowing plastic composition into the frame, agitating said plastic composition about each of said patterns, allowing the composition to set, reversing the frame with the plastic mass therein, superimposing a second frame upon said first named frame, flowing a plastic composition into said last named frame, allowing said composition to set, forming a gate cavity in one of the mold sections thus made by positioning independent gate patterns, so that portlons of the same will each engage a portion of each of said first-named patterns before pouring the plastic composition into the frame, separating the frames after the composition within the last named frame has set, and drawing each of said first named patterns and said gate patterns from the plastic mass.

3. The method or art of making molds consisting in placing a pattern within a frame upon a slab, flowing plastic composition into the frame, agitating said plastic composition about the patterns, allowing the composition to set reversing the frame with the plastic mass therein, positioning :1; ate pattern thereon with the lead thereo in engagement with the pattern embedded in the plastic composition, placed a second frame upon said first frame, flowing lastic composition into the said last name rame, allowing said composition to set, se rating the frames, drawing the patterns rom the lastic mass in each of said frames, and orming cooperating ton es and sockets in said mold arts respectively by formin a cavity in the mass of plastic in said rst named frame by means of a pattern placed 11 on the slab prior to the pouring of the p astic composition forming said mold part whereby the filling of the superimposed rame with the lastic composition will cause re 'stering of the ton ues to be formed by the astic mass in the ot er mold section.

4. T e method or art of making molds consisting in placing a plurality of independent patterns within a frame upon a slab, flowing plastic composition into the frame, itating said plastic composition about 12:51 of said patterns, allowing the composition to set, reversing the frame with the plastic mass therein, superimposing a second frame upon said first named frame, flowing a plastic composition into said last named frame, allowing said composition to set, forming a gate cavity in one of the sections thus made by positioning independent gate patterns, so that portions thereof will each engage a portion of each of said patterns, before pouring the plastic composition into the rame, separating the frames after the composition within the last named frame has set, drawing each of said first named patterns and said gate patterns from the plastic mass and forming coiiperating tongues and sockets in said mold parts respectively by forming a cavity in the mass of plastic composition in said first named frame by means of patterns placed upon the slab prior to the pouring of the plastic composition forming said mold part whereby the filling of the superimposed frame with plastic composition will cause registering tongues to be formed by the plastic mass in the other mold section.

5. The method or art of making molds consisting in placing a pattern within a frame upon a slab, flowing plastic composition into the frame, agitating said plastic composition about the pattern, allowing the composition to set, reversing the frame with the plastic mass therein, ositioning a gate pattern thereon with the ead thereof in engagement with the pattern embedded in the plastic composition, placing a second frame upon said first frame, flowing plastic comosition into the said last named frame, alowing said composition to set, separating the frames, drawing the atterns from the plastic mass in each of sai frames, forming a chill opening leading from a mold cavity formed in the mold part made in said first named frame and opening downwardly thereof whereby the initial chilling of the metal will be at a point remote from the ingate of the mold cavity when pouring.

6. The method or art of making molds consisting in placing a pattern within a frame upon a slab, flowing plastic composition into the frame, agitatmg said plastic composition about the pattern, allowing the composition to set, reversing the frame with the plastic mass therein, ositiomng a gate pattern thereon with the ead thereof in en gagement with the pattern embedded in the plastic composition, placing a second frame upon said first frame, flowing plastic composltion into the said last named frame allowing said composition to set, separating the frames, drawing the patterns from the plastic mass in each of said frames, and formin coiiperating tongues and sockets in said mol parts respectively by forming a cavity in the mass of plastic in said first named frame b means of a pattern placed upon the slab prior to the pouring of the plastic composition forming said mold part Whereb the filling of the superimposed frame wit the lastlc composition will cause registering of the tongues to be formed by the plastic mass in the other mold section, forming a chill opening leading from a mold cavity formed in the mold part made in said first named frame, and 0 enin downwardly thereof whereby the initial c illing of the metal will be at a point remote from the ingate of the mold cavity when pouring.

7. The method of making molds consistmg in placing a pattern wit in a frame upon a slab, flowing a plastic composition, comr smg plaster of Paris, kieselguhr and a uld, into the frame, agitating said plastic compos t on about the pattern, allowing the composition to set, positioning a gate pattern thereon with the lead thereof in engagement with the pattern embedded in the plast1c composition, placing a second frame upon the first frame, flowing plastic com osition into the said last named frame, alowing said composition to set, separating the frames, and drawing the atterns from the plastic mass in each of sai frames.

In witness whereof we hereunto aflix our slgnatures in the presence of two subscribwitnesses, this 28th day of December,

CHARLES PACK. LEO FRANK N OCK. 

